Chinese Optics Letters, Vol. 6, Issue 5, 342 (2008)
Study on an improved five-interferogram phase-shifting algorithm
Zhiyong Luo*, and Jialin Dai
- National Institute of Metrology, Beijing 100013
Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to \pi/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming to overcome this defect of traditional five-interferogram algorithm, an improved five-interferogram algorithm is presented. This improved algorithm not only keeps the high accuracy of traditional five-interferogram algorithm, but also does not need absolute equal step to unwrap phase. Instead, this algorithm only needs measuring phase-shifting. With the numerical simulation, the improved five-interferogram algorithm shows high accuracy, high reliability, and feasibility in practice. It is very valuable for accurate length measurement with Fizeau interferometer and Fabry-Perot interferometer.